The present invention relates to magnetic resonance imaging (“MRI”). It finds particular application in conjunction with reconstruction and deblurring of MRI images.
Magnetic resonance imaging is a diagnostic imaging modality that does not rely on ionizing radiation. Instead, it uses strong (ideally) static magnetic fields, radio-frequency (“RF”) pulses of energy and magnetic field gradient waveforms. More specifically, MR imaging is a non-invasive procedure that uses nuclear magnetization and radio waves for producing internal pictures of a subject. Three-dimensional diagnostic image data is acquired for respective “slices” of an area of the subject under investigation. These slices of data typically provide structural detail having a resolution of one (1) millimeter or better.
Programmed steps for collecting data, which is used to generate the slices of the diagnostic image, are known as an MR image pulse sequence. The MR image pulse sequence includes magnetic field gradient waveforms, applied along three axes, and one or more RF pulses of energy. The set of gradient waveforms and RF pulses are repeated a number of times to collect sufficient data to reconstruct the slices of the image.
For image reconstruction, the collected k-space data are typically reconstructed by performing an inverse Fourier transform (IFT). However, in certain experimental settings, such as spiral acquisition techniques and non-rectilinearly sampled data, image reconstruction is not simple and artifacts, such as blurring due to off-resonance effects have to be corrected. In addition, a large number of 2D-FFTs have to be performed if the data set is large, which may cause impractical and unacceptable delays in image processing.
It would therefore be desirable to provide more efficient methods for image reconstruction that render MR images with an image quality that is practically indistinguishable from that obtained with conventional image reconstruction methods, such as gridding algorithms and frequency-segmented off-resonance correction method used in spiral imaging.